<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="js/jquery-3.3.1.js"></script>
    <script>
        $(function () {
            $("button").click(function () {
                $("#hidden").show()
            })
        })
    </script>
</head>
<body>
<form action="">
    <label>密码：</label><input type="password" name="passwd" id="passwd"><br>
    <label>电子邮箱：</label><input type="email" name="email" id="email"><br>
    <button type="button">动态添加表单元素</button>
    <br>
    <div id="hidden" style="display: none">
        <label>联系电话：</label><input type="tel" name="phone" id="phone"><br>
    </div>

</form>
</body>
</html>
